1. Field of the Invention
This invention relates to lubricant additives and compositions thereof and more particularly to compositions comprising a major proportion of an oil of lubricating viscosity or a grease prepared therefrom containing a minor effective amount of a multifunctional additive consisting of borate esters of hydrolyzed hydrocarbyl alkoxides. Further, this invention relates to the described additives incorporated into lube oils in effective friction-reducing amounts.
2. Description of the Prior Art
It is well known that lubricants by definition reduce friction between moving surfaces; however, friction-reducing additives are agents which, when added to lubricants in minor amounts, significantly enhance the frictional or lubricity properties of those lubricants without modifying their other physical properties such as viscosity, density, pour point and the like.
Alcohols, for example, have long been known for their lubricity properties when formulated into lubricating oils and for their water scavenging characteristics when incorporated into fuel formulations. Hydrocarbon soluble epoxidized fatty acid esters prepared by the epoxidation of unsaturated carboxylic acid esters are also known to have been used as anti-wear and anti-friction additives in lubricants as described in U.S. Pat. No. 4,244,829. Borated hydrolysis products of 1-(2-hydroxyalkyl)-2-alkyl or alkenylimidazolines are known to be effective friction modifying additives as described in U.S. Pat. No. 4,273,665. Further, the use of vicinal hydroxyl containing alkyl carboxylates such as glycerol monooleate have also found widespread use as lubricity additives.
U.S. Pat. No. 4,410,438 to Horodysky discloses borated epoxide additives and lubricants prepared therefrom. In preparation of the additives, an epoxide is reacted with boric acid, boron oxide or an alkyl borate in the absence of added water.
It has now been found that borate esters of hydrolyzed hydrocarbyl alkoxides can significantly reduce friction of lubricants and add a new dimension of anti-oxidation and high temperature properties to lubricant compositions. The borate esters described herein also possess improved solubility characteristics over those of non-borated derivatives, especially in synthetic fuels. Additionally, these novel additives are non-corrosive to copper and possess anti-wear properties and the ability to provide anti-fatigue characteristics to lubricants or greases containing same.